This invention relates to a process and arrangement for monitoring belt or chain drives of internal combustion engines.
U.S. Pat. No. 5,689,067 discloses a process for monitoring wear of a timing chain in a motor vehicle engine by making measurements, in a non-contacting way, at a chain wheel on the crankshaft side and a chain wheel on the camshaft side, providing signals regarding the phase relation of the two wheels relative to each other, comparing the phase relation determined in real time during operation of the internal combustion engine to a predetermined nominal value and, if a deviation is present, generating a signal indicating unacceptable elongation of the chain. This process is intended to detect, in a timely fashion, unacceptably severe wear of the timing chain as a result of uniform elongation of the chain as well as elongation resulting from damage to an individual link. As a result of this monitoring, precautionary, and possibly unnecessary, replacement of the chain is avoided. Instead, the timing chain can be replaced only when it is truly necessary. Effects on engine operation that could result from an elongation of the timing chain are not discussed in this patent.
Independently of the elongation of such a timing chain, it is known, for example from U.S. Pat. No. 5,357,932, to undertake computer-controlled determination of the quantity of fuel injected in the individual cylinders of internal combustion engines which use a device for controlled change of the phase relation between a camshaft and the crankshaft driving it. A camshaft adjusting arrangement and a process for measuring the angular position of an adjustable camshaft are described in German Offenlengungsschrift No. 44 40 656 in which, when the engine is started, the first cylinder to be fired in a predefined firing order is determined, the angular position of the camshaft is measured and calculated, and this information is stored or utilized by an engine control unit for determining injection and fuel control parameters.